SGI Indigo² Capacitor Replacement Guide
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The aged electrolytic capacitors in an SGI Indigo² are mostly in its power supply, which SGI's owner's guides treat as a single replaceable part, with no component list.[1][2] weblacky notes that the Indigo² also has electrolytic capacitors in the GIO-64 backplane module and here and there on the system board, unlike the Indy board, which uses tantalum capacitors, though few failures of them had been reported when he wrote.[3] The board-level failures reported so far are shorted tantalum capacitors.[4] SGI's guides give no capacitor values for any of these assemblies.
Warning: the power supply runs from the mains. Unplug it, let the input capacitors discharge and check them with a meter before touching the boards.
Signs that the supply needs work
[edit | edit source]- The machine runs for 30 to 60 minutes and then trips out.[5]
- The fans twitch when the power button is pressed and the machine does nothing more.[6][5]
- An IMPACT machine chimes, clicks and restarts in a loop.[7]
- Freezes with no error, once memory has been ruled out, which weblacky attributes to ripple or a marginal rail.[8]
See also Capacitor Failure Symptoms.
Which supply
[edit | edit source]The teal Indigo² and the IMPACT models use different supplies. An IMPACT supply also powers the midplane through a ribbon cable and a twisted-pair cable, and a supply for an IMPACT Ready machine keeps those cables attached.[2][9] Part numbers owners have reported are 060-0027-001 (385 W, in a 1996 teal IP22 machine), 060-8001-001 (385 W) and 060-0027-002 Rev A (in an R10000 Solid IMPACT). IMPACT supplies came in 36 A and 48 A versions.[10][6][5]
The construction differs too:
- Non-IMPACT supply: only one end of the case comes off, so the end plate is removed, the boards are unscrewed and the assembly is tipped out of the case.[8] weblacky found the non-IMPACT supplies he opened "very doable".[11]
- IMPACT supply: a high-voltage board and a low-voltage board, mounted face to face and joined by heavy, short, soldered flat conductors from the main transformer that stop the boards being separated far. weblacky calls them a nightmare to handle, and says the conductors need a solder bath or a 300 W iron if they are ever unsoldered.[11][12] A later revision has connectors between the two boards, which makes it much easier to work on.[7]
Values reported by owners
[edit | edit source]| Assembly | Position | Value | Notes |
|---|---|---|---|
| IMPACT supply (later revision), low-voltage board | Not reported | 330 µF 6.3 V (red) | The only capacitors found out of specification when tested after removal; hard to remove |
| IMPACT supply (later revision), output | Not reported | 6800 µF 6.3 V | The owner tested three, found them good and left the other two in place |
| Audio board | C57 | 47 µF 20 V tantalum | Shorted and burnt out inductor L517 and a pad; the same position failed on an R8000 Indigo² |
The recap in the first two rows did not cure that supply's boot loop.[7] A UK repair firm that recapped a teal owner's supply fitted 105 °C parts.[13]
Advice from rebuilders
[edit | edit source]weblacky's points for Indigo² supplies:[12]
- Replace every electrolytic capacitor in the supply, the expensive ones included. He calls it a big mistake to change only the output capacitors.
- Do not fit modern low-ESR types chosen by value alone. Match the original parts' ESR, ripple rating, life and temperature rating, because changing the ESR can upset the supply's oscillation.
- Most failures are on the low-voltage side, which carries the fast recovery diodes and the output capacitors. Take the diodes out and test them, and lift one end of each resistor to check it against its marked value.
- A supply recapped before it is switched on after years of storage often works straight away; switching it on first is what often damages it.
Another member who has done several Indigo² supplies says the work is replacing the capacitors and a few of the transistors that control the switching.[13]
Record your own board before ordering: photograph it, then note each electrolytic's designator, capacitance, voltage, temperature rating, series, diameter, height and lead spacing.
Procedure
[edit | edit source]- Remove the supply from the machine; see General Maintenance.[1]
- Open the case. On a non-IMPACT supply, remove the end plate, unscrew the boards and tip them out.[8]
- Photograph and record every electrolytic capacitor.
- Remove and replace the capacitors one position at a time, observing polarity. Use a desoldering gun; the IMPACT owner found the job hard even with one, and suggests a board preheater.[7]
- Test the diodes and resistors on the low-voltage side out of circuit while the board is open.[12]
- Reassemble, and make the first start through a bulb current limiter (a 300 W bulb or two 150 W bulbs). A bulb that throbs while the supply seems dead means the supply is restarting in overcurrent protection.[12]
Checks after the work
[edit | edit source]SGI publishes no rail table for the Indigo². An owner who measured a teal machine with Extreme graphics at its board connectors found +5 V, +12 V, −5 V, −12 V and 3.3 V rails present.[6] Run the machine through its power-on tests and the IDE diagnostics, and leave it running for at least an hour, since the reported faults include supplies that trip after 30 to 60 minutes.[5] See SGI Indigo² Troubleshooting Guide.
Related pages
[edit | edit source]- SGI Indigo²
- SGI Indigo² General Maintenance
- SGI Indigo² Troubleshooting Guide
- SGI Power Indigo²
- Capacitor Failure Symptoms
- Recommended Tools
References
[edit | edit source]- ↑ 1.0 1.1 Silicon Graphics, Indigo2 Workstation Owner's Guide, 007-9096-050, 1996, pp. 176–183 (File:SGI Indigo2 Workstation Owner's Guide (007-9096-050).pdf). Power supply as a replaceable part.
- ↑ 2.0 2.1 Silicon Graphics, Indigo2 IMPACT Workstation Owner's Guide, 007-2849-004, 1996, pp. 272–282 (File:SGI Indigo2 IMPACT Workstation Owner's Guide (007-2849-004).pdf). IMPACT and IMPACT Ready supplies and midplane cables.
- ↑ "hello network, lots of questions", IRIX Network forums, weblacky, forums.irixnet.org. Electrolytics in the Indigo² GIO-64 backplane module and system board.
- ↑ 4.0 4.1 "My SGI Indigo2 audio board give off magic smoke", IRIX Network forums, 8 October 2021, forums.irixnet.org. C57 47 µF 20 V tantalum; L517.
- ↑ 5.0 5.1 5.2 5.3 "Indigo2 PSU woes and questions", IRIX Network forums, 23 July 2022, forums.irixnet.org. Part 060-0027-002; 36 A and 48 A versions; supplies tripping after 30–60 minutes.
- ↑ 6.0 6.1 6.2 "Indigo2 power on issue", IRIX Network forums, February to August 2019, forums.irixnet.org. Rails measured on a teal Extreme machine; supply 060-8001-001; twitching fans.
- ↑ 7.0 7.1 7.2 7.3 7.4 "Indigo 2 Impact Power Supply Boot Loop", IRIX Network forums, 16 July 2025, forums.irixnet.org. Later IMPACT revision with board connectors; 330 µF 6.3 V and 6800 µF 6.3 V capacitors; tools used.
- ↑ 8.0 8.1 8.2 "I aquired a Indigo 2 and 2 Indys - should I first recap the PSU?", IRIX Network forums, August 2026, forums.irixnet.org. Non-IMPACT supply construction; weblacky on freezes.
- ↑ "SGI Indigo2", Wikipedia, revision of 22 June 2026, en.wikipedia.org/wiki/SGI_Indigo2. IMPACT-ready power supply and riser.
- ↑ "Repair Request: Indigo2 powersupply", IRIX Network forums, 12 July 2026, forums.irixnet.org. 385 W supply 060-0027-001.
- ↑ 11.0 11.1 "Indigo2 power on issue", IRIX Network forums, weblacky, 15 August 2019, forums.irixnet.org. Non-IMPACT supplies doable; IMPACT supply's soldered flat conductors.
- ↑ 12.0 12.1 12.2 12.3 "Two Indigo2 PSUs. Combine half of one with the other?", IRIX Network forums, weblacky, 13 November 2021, forums.irixnet.org. Recapping advice, ESR, low-voltage diodes, bulb limiter, soldered conductors.
- ↑ 13.0 13.1 "Re-capped Indigo2 PSU", IRIX Network forums, 21–26 October 2018, forums.irixnet.org. Professional recap with 105 °C capacitors; capacitors and switching transistors replaced in other supplies.